code: def test_output_extractall_merge_frame_is_not_None(
      test_returns_dataframe,
  ):
      """
      Test output when `string_function` is "extractall"
      and `merge_frame` is not None.
      """
      expected_output = test_returns_dataframe["text"].str.extractall(
          r"(?P<letter>[ab])?(?P<digit>\d)"
      )
      expected_output = test_returns_dataframe.join(
          expected_output.reset_index("match"), how="outer"
      ).set_index("match", append=True)
      result = test_returns_dataframe.process_text(
          column_name="text",
          merge_frame=True,
          string_function="extractall",
          pat=r"(?P<letter>[ab])?(?P<digit>\d)",
      )
      assert_frame_equal(result, expected_output)
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 26 for calling a global function with example usage: test_output_extractall_merge_frame_is_not_None(test_returns_dataframe) without return types